The present invention relates generally to systems for transferring dry free flowing bulk materials in the form of particulate or pulverulent materials or the like, and more particularly to a novel transfer vessel for use in such systems.
Systems for transferring bulk products such as dry flowable particulate or pulverulent materials are generally known. Such systems find particular application in conveying bulk materials such as cement, ash, soot, powdered minerals, flour, and coal dust and the like, and generally employ a substantially closed transfer vessel or tank having an inlet opening through which the particulate material may be drawn from a source, such as the hold of a ship or a railcar, after which the flowable material is discharged at a discharge outlet for transfer by way of a pneumatic flow line or the like to a different location such as a storage silo. See, for example, U.S. Pat. No. 3,372,958 to R. R. Black and U.S. Pat. No. 3,861,830 to R. D. Johnson. The systems disclosed is these patents operate on the principle of creating a vacuum or suction within the vessel to effect input loading of flowable particulate material into the vessel until the vessel is substantially full at which time a positive fluid pressure is introduced into the vessel so as to force the material from a discharge outlet into a discharge line in which the material is pneumatically conveyed to a remote storage or production facility. Such filling and discharge of the vessel is generally effected automatically in an alternating cyclical manner by means of a valving control arrangement operative to alternately apply suction and pneumatic pressure to the vessel.
A significant drawback or disadvantage found in many of the known pneumatic conveying systems of the aforedescribed type employing substantially closed transfer vessels or tanks is that rather complex valving and associated flow conduits or lines are generally mounted on and externally of the pressure vessel and extend upwardly therefrom so as to significantly inhibit transportability of the vessels without undertaking substantial disassembly. This is due in part to regulations limiting the over-the-road height for vehicles and associated loads due to viaducts and overpasses and the like found in contemporary highway systems.
Another significant drawback in the prior pneumatic conveying systems employing transfer vessels as aforedescribed is that, to the extent they employ filter arrangements internally of the transfer vessel to prevent entry of particulate material into the suction line, such filter arrangements substantially diminish the effective useful volume or load capacity within the vessel, thus substantially reducing the efficiency of the corresponding conveying system.
Still another drawback in the prior pneumatic conveying systems which employ transfer vessels of the aforedescribed type is that they fail to suitably maintain a predetermined uniform design pressure within the transfer vessel. Because of this, the pressure within the vessel undergoes substantial variations with the result that the conveying efficiency of the transfer vessel is substantially less than optimum which leads to significantly increased cost per unit of material transferred.